A recent survey of dentists suggested that occupational exposure to anesthetic gases might be a health hazard to the dentist, the dental staff, and their families. Since nitrous oxide is the oldest and the most widely used anesthetic agent in the current dental practice, there is a need for continual review of the long-range biological effects of low-level nitrous oxide exposures. The proposed research project will initiate the following multi-disciplinary investigations regarding the biological effects of low-level exposures of nitrous oxide in a systematic fashion: a) genetic effects in two inbred strain of mice and Sprague-Dawley rats, b) development effects on mouse and rat embryos, and c) morphological and biochemical effects on the liver, lung, kidney, testes and drug-metabolizing enzymes of mice and rats.